Hypertension is a strong risk factor for cardiovascular disease and causes death and disability in our rapidly expanding older population. Although several health organizations recommend exercise for milder forms of hypertension, few older persons were subjects in the research upon which these recommendations are based. The specific aim of this study is to determine whether exercise training reduces blood pressure in men and women, ages 55-75 years, with high normal blood pressure or mild hypertension. Participants will be randomly assigned to either 6 months of exercise training, or to a control group. We will also measure whether exercise training improves blood cholesterol, glucose (sugar), insulin, body fat, heart size and function, and the condition of blood vessels using a variety of testing methods. The results of this study will help expand the scientific knowledge that defines exercise guidelines for older men and women at risk for cardiovascular disease because of their blood pressure level.